There seems little doubt that chemicals responsible for the peppery bite of chili peppers can inhibit the accumulation of body fat. It’s not only been illustrated rather convincingly in rodents, but also reported a few months back to operate in people. The question has been how peppers do this. Korean researchers now describe peppery changes in genes that appear to underlie fat-shunning properties — ones that point to how chili’s fiery chemistry might be harnessed to fight obesity.